Our laboratory has focused on factors that influence host responses to tumors and may adversely influence responses to immunotherapy. We have identified an immunoregulatory factor produced by a variety of human tumors that profoundly inhibits in vitro cell mediated immune responses. We are in the process of characterizing and purifying this factor and also determining its role in vivo. We are developing sensitive new techniques to measure cellular and humoral immune responses to human tumor-associated antigens. These included an automated micro slide leukocyte adherence inhibition test utilizing cryopreserved lymphocytes and an enzyme-linked immunoabsorbant solid-phase assay using soluble human tumor-associated antigens. We have collected over 25 extracts from human primary sarcomas as well as metastases. Using autologous lymphocyte and sera, we are analyzing the distribution of tumor associated antigens on primary tumors and their metastases. Concurrently, we have established a murine melanoma model with cloned primary and metastatic cell lines to test various therapeutic options.